The choice structure and cyclic structure of C language

Basic understanding of 1.if

         /* If Judgment statement format     if (conditional expression 1)     {        statement 1 ...     }     else if (conditional expression 2)     {        Statement 2 ...     }     else     {        Statement 3 ...     }          If the conditional expression 1 is true, only statement 1 is executed.     if the condition Expression 2 is established, only executes statement 2,      if none of the above conditions are true, execute statement 3          //if can be nested using     if (conditional expression 1)     {        if (conditional expression)        {             }     }     else     {          }          */

Let's have a little practice practiced hand.

    int a = ten;    if (a >= 2)         {            if (a <= 5) {                printf ("A is a number of one 2~5 \ n");            }        else            {                printf ("A is not a number between 2~5 \ n");}        }    else        {            printf ("A is not a number between 2~5 \ n");        }            

2.switch

/*switch (conditional expression)    {case        A:            statement 1 break            ;        Case B:            statement 2 break            ;            ....        Default:            statement 3 break            ;    }    If the return value of the expression is a, then EXECUTE statement 1, if the return value is B, then execute statement 2, if none, then execute Statement 3.        Note: The    return value of the conditional expression of 1.switch must be shaped, or can be converted to an integer type (character type)    2.case can only be the return value of an integer type/integer/can be converted to an integer type can also (character is the essence of ASCII code    3. If break is not written, it will cause penetration and execute the statement sequentially until it encounters a break.    4. No matter what the default is, it is the last execution */

Let's have a little practice.

    int a = 3;    Switch (a)    {case        1:            printf ("a = 1");            break;        Case 2:            printf ("a = 2");            break;        Case 3:            printf ("a = 3");            break;        Case 4:            printf ("a = 4");            break;        Default:            printf ("All Wrong");            break;    }

3.while

    /*    while format     while (conditional expression)     {        statement (loop body);        ......     }     When the return value of the conditional expression is true, the statement in the while is executed, and when the statement in while is executed, the expression is judged again and again, and the statement continues to execute until the conditional expression is false     */

Go on a little exercise

    int number = 0;    int count = 0;    while (number <=)    {        if (numbers% 7 = = 0)        {            //proves that the current count is a multiple of 7            count++;//similar counter            printf (" A multiple of 7 is%i\n ", number);        }        number++;    }

4 Do While

    /* do    {        statement;        ...    } while (conditional expression);        The difference between do and while: the     first thing to judge the true and false of the conditional expression is to do the loop doing while     : Run the loop first, then judge the true or false of the expression.     

The choice structure and cyclic structure of C language